(A) Field of the Invention
The present invention relates to a wireless transmission apparatus, and more particularly, to a wireless transmission apparatus, which is powered by a computer through a universal series bus (USB) port.
(B) Description of the Related Art
FIG. 1 is a schematic diagram showing the wireless connection between a computer 10 in a wireless local area network (WLAN) 22 and a wide area network (WAN) 99 according to the prior art. As shown in FIG. 1, the computer 10 is positioned within the WLAN 22, and connected to the WAN 99 through a wireless-LAN access point (AP) 20. The AP 20 is powered by commercial power through a power transformer.
FIG. 2a is a functional block diagram of a wireless network card 30 installed in the computer 10 according to the prior art. As shown in FIG. 2a, the computer 10 comprises a processor 12, a chipset 14, a PCMCIA controller 16 and a PCMCIA port 18. The wireless network card 30 can exchange data with the computer 10 through the PCMCIA interface, and uses IEEE 802.11 communication protocol to exchange data with the AP 20. The wireless network card 30 comprises a system bus 32, an interface processing unit 34, a PCMCIA port 38 electrically connected to the computer 10, an antenna 36 for transmitting data to the AP 20 and a radio frequency (RF) circuit module 39 electrically connected to the antenna 36. The interface processing unit 34 is used to convert the data from the PCMCIA interface of the computer 10 into the format of IEEE 802.11, or convert the data from the AP 20 into the format of the PCMCIA interface.
FIG. 2b is a functional block diagram of a wireless network transmission module 11 embedded in the computer 10 according to the prior art. This design may become the mainstream in the future market, however the product price is high and personal computer (PC) users can not refit their PCs to use this design for accessing data from Internet. Consequently, the above-mentioned wireless network cards are still dominant in the market. As shown in FIG. 2b, the processor 12 and the chipset 14 of the computer 10 communicate with the wireless network transmission module 11 directly through a bus of the computer, and then conduct wireless data transmission by the embedded antenna, wherein the wireless network transmission module 11 can consist of a wireless network controller 13 and a radio frequency circuit 15.
Generally speaking, a driver of the processor drives the operation of the wireless network card 30. Therefore, the computer can not be connected to the AP 20 through a wireless network card 30 unless such a driver is installed in the computer 10. During the driver installation, users must check whether or not the driver of the wireless network card 30 supports the operating system of the computer 10. Windows, Linux and Unix are the primary operating systems for the time being, wherein there are several versions for the Windows operating system, such as 98/ME/NT/2000/XP/CE/Pocket. To access data from the wireless network through the wireless network card 30, users must check whether or not the driver supports the operating system of the computer 10 when installing the driver of the wireless network card 30, and the installed driver must be the correct version for the computer 10. The installation of drivers are complicated and users may be confused, thus a wireless transmission apparatus that does not require any driver installation and supports Plug & Play function is in demand. For the moment, wireless network transmission apparatus is designed as an independent apparatus with Plug & Play function, such as the Ethernet, wherein the apparatus needs an independent power supply and is powered by commercial power through an external transformer.
FIG. 3a is a schematic diagram showing the connection between a wireless network transmission apparatus 90 and a computer 60 according to the prior art. As shown in FIG. 3a, the computer 60 exchanges data with the wireless transmission apparatus 90 via the data transmission line 72. Since the wireless transmission apparatus 90 is powered by commercial power, users must prepare a power line and find a power plug to access data from the wireless LAN every time and everywhere when they want to use it. This is really inconvenient for those who have no regular work location and need to change workplaces frequently. Obviously, the wireless network access scheme of the prior art needs to be improved.